The present invention relates to an automatic toilet flushing system for automatically flushing a toilet after each use.
Such automatic flushing systems are particularly useful in public toilets, for example in restaurants, public buildings, and so on, where users sometimes neglect to flush the toilet manually after use, resulting in an unsanitary condition for subsequent users. They may also be used for private toilets.
A standard manually flushable toilet comprises a toilet bowl connected to a toilet tank having a valve controlled water inlet for filling the tank with water, and a flush valve connecting the tank to a toilet bowl for flushing the toilet. A handle is provided on the tank for opening the flush valve. The water inlet valve is float controlled to be closed when the water reaches a predetermined level in the tank. The handle generally moves a lever arm within the tank which is connected by a chain to the flush valve, the flush valve closing automatically when the handle is released and the tank empties.
Automatic flushing devices for use with conventional toilets have been proposed in the past, but these have generally been relatively complex and expensive, and have involved substantial modification to the standard manual toilet.
One example of a previous automatic flushing device is described in U.S. Pat. No. 3,780,384 of Rivelle. In this device a seat-actuated valve provides a regulated flow of water to a flush valve operator for opening the flush valve. The seat-actuated valve is connected to the toilet water supply pipe and is "armed", or filled with water, when the tank is filling. When the valve is actuated by a user leaving the toilet seat, the water already in the valve is displaced to actuate the flush valve operator. This system is relatively complex, involving bypassing the water inlet pipe outside the toilet tank, and includes two relatively complex valve actuating mechanisms.
U.S. Pat. No. 3,056,142 of Chin shows a toilet flushing device in which a valve actuating link connected to the manual flush arm of the toilet is reciprocated by pivotal movement of a toilet seat between its raised and lowered positions. the seat is spring loaded into its raised position on removal of weight from the seat. A similar weight operated device is described in U.S. Pat. No. 4,329,745 of Aguero.
Thus, up to now automatic toilet flushing devices have generally involved relatively complex mechanical linkages which can be difficult and expensive to install. Electronic toilet flushing systems have generally been avoided since such systems were believed to require the introduction of electrical leads into the tank, which would clearly be unsafe.